Dominion proposes 186-mile underground HVDC power line across Virginia
LOUDOUN COUNTY, Va. (UI) — Dominion Energy Virginia has proposed a 186-mile underground high-voltage direct current (HVDC) transmission line designed to deliver additional electric capacity to Loudoun County, one of the fastest-growing power demand centers in the region.
The project would connect Dominion’s Heritage substation in Brunswick County to the Mosby substation in Loudoun County, running entirely underground and largely within existing transmission rights-of-way. The proposal is part of PJM Interconnection’s Regional Transmission Expansion Plan, which evaluates projects to address grid constraints across 13 states and Washington, D.C.
According to county documents, the project is the only shortlisted PJM proposal that would terminate directly inside Loudoun County’s primary load center, a factor cited as key to meeting rapidly growing residential, commercial and data-center demand. The line is expected to follow existing overhead corridors, reducing the need for new property acquisitions and limiting surface disruption.
County staff recommended that the Loudoun County Board of Supervisors submit a letter of support for the proposal, emphasizing the benefits of underground HVDC construction, including added capacity without new overhead infrastructure, reduced community impacts and long-term cost efficiency. The board approved the letter during its Dec. 2 business meeting.
PJM opened its most recent proposal window in mid-2025 after identifying system deficiencies tied to rising regional demand. Dominion’s HVDC project is among a group of shortlisted candidates expected to receive final review by the PJM board in early 2026.
No fiscal impact to the county is associated with the letter of support. Any future construction would be subject to additional planning, engineering, and public engagement phases before moving forward.
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